Funding in the first three cycles of this grant provided support of the Drosophila RNAi Screening Center (DRSC) at Harvard Medical School, allowing us to bring to the community a unique state-of-the-art infrastructure for high-throughput RNAi screens (RNAi-HTS) in Drosophila cells. To date, we have facilitated many full-genome screens, smaller screens and other projects, resulting already in more than 125 publications on screen results, methods, meta-analysis, etc. Reagent information and screen datasets are available for search or download online at our own website, www.flyrnai.org, as well as at other sites such as FlyBase, GenomeRNAi and NCBI PubChem BioAssays. Over the years we have designed, generated, and refined our RNAi libraries and added libraries for over-expression screens and interrogation of miRNA function. Our RNAi libraries offer exceptional quality and coverage, comprising nearly 35,000 unique, high-quality double stranded RNA (dsRNA) reagents targeting a total of about 14,000 protein-coding and non-coding Drosophila genes. We also designed and maintain an extensive laboratory information management system (LIMS) and database, as well as a website that provides free access to protocols, publications, datasets, and an increasing number of online software tools. Altogether, we have succeeded in establishing ourselves as an integrated center for screening and technology transfer, serving the widest possible community of researchers. Through support of both on-site and off-site screens using our high-quality libraries, researchers are continuing to conduct innovative cell-based assays to address fundamental cell biological questions and disease-related topics, taking advantage of the efficiency, low gene redundancy and gene conservation offered by the Drosophila cell system. The experience we have gained since 2003 has shaped our view of how to further expand the scope and impact of the DRSC through continued support of on-site and off-site screening as well as rapid transfer of new technologies (e.g. CRISPR-Cas technologies) to the community. In this competing renewal, we seek continued support for the DRSC resource so we can keep providing the state-of-the reagents, experimental and informatics infrastructure that makes Drosophila functional genomic screening accessible to the widest possible group of researchers. Among the reasons our efforts are critical is that unlike for functional genomics studies in mammalian cells, commercial companies have no commitment to provide the community with reagents, databases and software tools for Drosophila functional genomics screens and analyses.